Sub-GHz Transceiver Crystal Passivation under Extended High Current Transmit Pulses
Sub-GHz transceiver crystal passivation prevents drive-level dependency shifts and frequency pulling during extended high-current power amplifier transmit pulses.
LoRaWAN SF12 Transmit Duty
Meaning
Transmit parameters governing the time on air for low-power wide-area network devices using spreading factor twelve represent the most restrictive configuration for long-range data transmission. This operational limit, known as LoRaWAN SF12 transmit duty, is defined by the high time on air required to send packets at this spreading factor. The long transmission duration consumes significant battery power and channel capacity.
Devices must limit these transmissions to comply with regional duty cycle regulations.
Time on Air
Spreading factor twelve uses the highest number of chirps per symbol, which improves receiver sensitivity at the expense of transmission speed. A small payload can take over one second to transmit, which is much longer than lower spreading factors. This extended transmission time limits the number of packets a device can send in a given day.
Duty Cycle
Unlicensed sub-gigahertz bands require all transmitters to adhere to duty cycle limits, which are usually set at one percent. A device transmitting under LoRaWAN SF12 transmit duty constraints must wait for an extended period before sending another packet to remain within the law. This waiting period restricts the real-time reporting capabilities of the sensor node.
Battery Impact
Long transmit times draw high current from the battery for several seconds during each transmission. System designers minimize the use of spreading factor twelve to prolong the operating life of the device.